Ellman’s Reagent

Ellman's reagent is a versatile, water-soluble compound for quantifying free sulfhydryl groups in solution. It reacts with a free sulfhydryl group to yield a mixed disulfide and 2-nitro-5-thiobenzoic acid (NTB), a measurable yellow colored product at 412nm.

Ellman's reagent is very useful as a free sulfhydryl assay reagent due to its high specificity for -SH groups at neutral pH, high molar extinction coefficient and short reaction time.